1. Field of the Invention
The invention relates generally to a transmission for a vehicle, and, more specifically, to a transmission for a vehicle, in which a shifting mechanism and a differential mechanism are integrally provided.
2. Description of the Related Art
A housing of a conventionally-used transmission for a vehicle is described in, for example, Japanese Patent Application Publication No. 2004-36633 (JP-A-2004-36633). With the housing described in JP-A-2004-36633, the amount of lubricating oil in the housing is reduced, the lubricating oil is more appropriately supplied to elements that need lubrication, and resistance, which is caused when, for example, a final gear stirs the oil, is reduced. According to JP-A-2004-36633, a partition provided between a differential chamber and an oil pan chamber separates these chambers from each other. The differential chamber has a bottom portion, and houses a differential unit. The oil pan chamber is communicated with the space inside an oil pan. A through-hole is formed in the partition.
A transmission for a vehicle is described in Japanese Patent Application Publication No. 06-159484 (JP-A-06-159484). According to JP-A-06-159484, an oil strainer is appropriately arranged in a limited space without use of a connecting device. In addition, the oil strainer is easily fitted at an appropriate position in a case without reduction of sealing performance between an oil supply port and the oil strainer.
According to the technology described in JP-A-2004-36633, the oil, which is accumulated at the bottom of the differential chamber, is returned to the oil pan chamber through the through-hole. However, if the viscosity of the oil increases when the temperature of the oil is low and the oil drawn upward adheres to, for example, a wall face of the differential chamber, the amount of the oil which is returned to the oil pan decreases. Under this condition, the air may be sacked into a suction opening of the oil strainer.